The red soil region in southern China is highly susceptible to erosion due to monsoon rainstorms and soil wet-dry rotations. This study analyzed the characteristics of erosion runoff and sediment, as well as the evolution of soil erodibility, in naturally restored woodland and bare land plots using 40 years of monitoring data from the Ecological Experimental Station of Red Soil. The results showed: (1) Both woodland and bare land soils exhibited an increase in sand content and a decrease in clay content over time, while organic matter content significantly increased, with woodland showing higher accumulation rates. (2) Runoff patterns differed markedly—bare land exhibited rainfall-dependent fluctuations, whereas woodland runoff declined steadily, decreasing 2.5-fold following shrub-grass establishment between 1993 and 1996. (3) Sediment yield correlated with runoff trends; bare land"s sediment peak preceded the runoff maximum, indicating a transition in erosion resistance during 1994–1995, while woodland sediment approached zero after 1996. (4) The K factor for bare land initially increased, then declined with organic matter accumulation, whereas the K factor for woodland showed the opposite trend due to progressive clay loss. This study demonstrates that long-term vegetation restoration effectively controls runoff and sediment yields, while bare land remains erosion-prone despite slight improvements. These findings provide a scientific basis for erosion control and ecological restoration in red soil regions.